Distillation of tar



Feb. 9, 1932. s. P. MILLER 1,844,390

DISTILLATION OF TAR Filed Feb. 5, 1927 5 Sheets-Sheet 1 (0/715 UVE/VB/VTTER) [lass-ans? #010,404 A l/euokl 33 k WWW" INVENTOR 5 WEWZEYMW ATTORNEYS Feb. 9, 1932.

s. P. MILLER DISTILLATION OF TAR Fi led Feb. 5. 1927 5 sheets-sheet 2 i/6, INVENTOR PM W ATTORN EYS Feb. 9, 1932. s. P. MILLER DISTILLATION OF TAR Filed Feb. 5, 1927 5 SheetsShee't 4 J WPWVENTER m ATTORNEYS Feb. 9, 1932.

S. P. MILLER DISTILLATION OF TAR Filed Feb. 5. 192'? 5 Sheets-Sheet 5 W 'alNVENTOR Ext 0 o o o o O O O O O o oooo oo O 0 O O O O O O O O O 0 ATTORNEYS operation pass the plant and Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE s'ruamr PABMELEE MILLER, or TENAFLY,

- N. Y., a \conrorwrron or NEW JERSEY COMFAN Y, OF NEW YORK,

NEW JERSEY, ASSIGNOB TO THE BARRETT DISTILLATION or TAR Application filed February 5, 1927. Serial No. 166,081.

This invention relates-to improvements in the distillation of tars and the production of pitches and distillate oils therefrom, and includes a new method of tar distillation and of pitch production. More particularly, the invention relates to the recovery of desirable products from coal carbonization and distillation plants such, for example, as by-product coke ovens, gas retorts, etc. The invention will be .described more particularly in connection with the operation of by-product coke ovens.

In the ordinary operation of by-product coke ovens the gases produced by the coking from the individual ovens through uptake pipes and goose-necks to a doilector main common to a battery of ovens. The coke-oven gases leaving the ovens at high temperature are cooled in the collector main and in condensers connected therewith to separate tar constituents therefrom. In many cases the gases are also substantially cooled in the goose-necks by sprays of am- P 'the collector mam or mains in connectlon monia liquor. The separated coal tar is com monly shipped or conveyed to tar distillation plants where it is subjected to distillation to produce pitches and various other products.

Owing to the high temperature of the gases from the coke ovens, and particularly because of the enormous amount of heat carried thereby, the successful operation of the collector main in connection with these ovens has always been a serious problem. The heat carried by,the gases which leave the ovens at a temperature-of approximately 700 or higher isfrom twenty to thirty-five times that required for the distillation of all of the tar contained in the gases. A certain amount of heavy tar or pitch may separate in the collector main and suchtar or pitch is subjected to the distilling eifect of the gases at high temperature with the resulting formation in the main of solid hard pitch which can, in some cases, be removed only by shutting do I scraping or digging it out. It is customary to flush the main. with a mixture oftar and ammonia li uor or with ammonia liquor alone, but thls practice does not always avoid the difiiculty. In fact, the

use of water or ammonia liquor aggravates main with a large amount the situation in some cases because the pitches formed in the main are insoluble in water or ammonia liquor and hence are not flushed out unless an extremely large amount of the liquor is employed.

The use of a'large quantity of ammonia liquor for flushing the collectormain introduces a new difficulty because of the resulting lowered temperature of the gases. Thus, by spraying ammonia'liquor into the collector main in s'utficient quantity to prevent accumulations of pitch therein the temperature of the gases may be so reduced that aconsiderable proportion of the valuable oil constituents which are present in the gases are condensed and are thrown down with the tar and can be recovered therefrom only by subsequent distillation.

by the coke-oven gases to distill the tar and taken of the heat carried separate the volatile products therefrom so that the latter can be recovered independently of the pitch which then constitutes a separate product of the operation.

According to the present invention the hot coke-oven gases as they come from the coke ovens are utilized for the distillation of tar and the separation of vaporizable oils therefrom by spraying or otherwise bringing the tar into-intimate contact with the hot cok'eoven gases in the collector main while the gases are at a temperature high enough to accomplish the desired distillation; and pitching of the main is prevented by flushing the of hot tar or pitch, in excessof that distilled by the hot gases. The large excess of tar or pitch circulated through the main is continually or intermittently drawn off as pitch, and can be in part recirculated through the main, with addi-v tional tar or pitch to be distilled, or it can be drawn of! as a finished product, or further distilled by a separate operation. -Where a plurality of short collector mains are employed, as hereinafter described, the tar and pitch may be passed in succession through several of the mains to effect progressive distillation thereof. Pitches having varying qualities and different characteristics, depending upon the regulation of the distillation operation, may be obtained.

The spraying of tar into hot coke-oven gases results in partial cooling of these gases from the temperature at which they normally escape from the coke oven, e. g., around 600 to 700 C. or in some cases much higher. The temperature of these gases is sufficiently high and the volume of non-condensable gases is so great, that the effective distillation of the tar can be accomplished by an intimate and regulated contact of tar with the hot gases. The amount of tar supplied and the intimacy and time of contact of the particles of the tar spray with the gases, and, therefore, the nature and amount of oil distilled therefrom,

can be varied. Effective distillation can be accomplished with a temperature drop of the gases while passing through the tar spray of, for example, 100 C. although with increased amount of tar or increased intimacy and time of contact a greater drop in temperature and increased distillation of oil can be attained.

The tar in turn will be heated by the hot gases and its temperature may be very considerably raised. Part of the heat, however, is employed in vaporizing liquid constituents of the tar Without corresponding increase in temperature thereof so that the maximum temperature of the tar and of the resulting pitch may, in some cases, be considerably below that of the gases. In order to avoid pitching of the main it is important that the tar used to flush the main, and that circulating thrpugh the main, be kept hot so that it is thinly fluid and so that any pitch formed will be dissolved and blended therein. So ldng as the pitch is kept sufficiently hot, it is thinly fluid, and by omitting the cooling effect of excessively large amounts of ammonia liquor, this thinly fluid condition can be readily insured.

The distillation of tar in the collector main may be accomplished in a variety of ways involving the intimate contact of the tar with the gases therein. Preferably the introduction of ammonia liquor to the collector main is avoided except as hereinafter described and in place thereof the main is flushed with a sufficient quantity of tar oroil or tar and -oil to ensure against any accumulation of heavy pitch in the main. This object is readily accomplished if a suflicientquant ity of the flushing medium is provided, and if the temperature is kept high, because the heavy pitch, if it is formed, is soluble in thehottar or oil used and any accumulation will be dissolved and carried along with the stream of hot tar which flows through the main. All or a portion of the tar can be introduced advantageously through spray nozzles provided for that purpose in the collector main and in the connected goose-necks. In addition to the tar or oil introduced through the spray nozzles in the collector main and goose-necks, tar or oil or mixtures thereof can be circulated through the main by introducing it at one end thereof and withdrawing it from the other. There are two important requirements, the first of which is the intimate mingling of the tar with the gases from the ovens at a high temperature to effect the desired distillation and the other is the constant washing or flushing of the surfaces of the main with a large excess of hot tar or oil or mixtures thereof to prevent an accumulation thereon of heavy pitch. Both of these purposes can be accomplished by the use of spray nozzles. It can be accomplished likewise by the use within the main of suitable mechanical agitating devices actuated to maintain a constant and violent agitation of the tar as it flows through the main so that the tar is splashed or thrown into the stream of cokeoven gases and onto the exposed surfaces of the main.

The agitation can be accomplished by the use of a rotating shaft running lengthwise of the main or a number of such shafts run ning across the main with suitable paddles or vertical shafts with paddles thereon. Similarly, rotating cones or other agitating and splashing devices may be dis osed in the collector main and arranged to be actuated for the purpose of throwing the tar into the stream of gases and upon theexposed surfaces of the main. Discs, plates, or spines on rotating shafts will achieve the same purpose. The required agitation can also be accomplished by the introduction of conipressed gases such, for example, as fuel or coke-oven gases or steam through a suitable distributor pipe immersed in the tar or suction Ts '(McDaniel type ejector-s) may be located in the main with their suction ends beneath the level of the tar therein. If the nozzles of the ejectors are allowed to extend above the surface of the tar, a spray of tar will be thrown up into the gas.

I do not, however, claim specifically herein the atomizing or spraying of the tar and pitch by mechanical agitating devices located in the main and'acting on the tar and pitch in the main, since such specific method is claimed in my companion application Serial No. 160. 082, filed of even date but such method is included within the broader scope of the present invention.

Although indiscriminate cooling of the gases in; the collector 'main as heretofore practiced is to be avoided, it may be. desirable to introduce water or ammonia liquor 'with tar and oils.

with the tar which is sprayedinto the col more readily with water because of the higher specific and latent heats of water as compared It is possible, therefore, to add water or ammonia liquor in the proportion required to remove all heat except that needed for the distillation of the tar. When hard pitch is desired less Water can be added and'proportionally more tar or oil will be passed through the main. Cooling of the gases to a regulated extent so that the gases will retain only the required distillation capacity can be accomplished also by the addition thereto of cold gases such as fuel gas, cooled coke-oven gas, flue gas and ammonia gas. Additional heat may be made available by passing such gases over the incandescent surface of the coke in the ovens and thence through the uptakes to the col-'.-

. lector main with the normal coke-oven gases The distilling capacity of the gases is thus increased in proportion to the heat which is carried from the'ovens The distilling capacity of the gases from a single coke-oven battery is greatly in excess of that required for the distillation of the amount of tar which that single cokeoven'bat'tery produces so that the tar from a considerable number of coke-oven batteries can be distilled by the hot gases from a sin- Consequently, to maintain the ordinarilynecessary to provide an amount of tar verymuch in excess of that produced by the single battery ,duced to that which will distill the available tar as, for example, by using such gases in.

l a separate short collector main.

here several coke-oven "batteries are op erated at a single plant, e. g.', twenty batteries, the tar from several orall the batteries can be distilledon asingle battery, hy-op-i eration according to the present invention.

Where there isonly one or a few-batteries,

the tar canbe recovered in normal operation; e. g.,with ammonia liquor spray in the collectormain, and after a suflicient amount-of tar has accumulated it may then be distilled in the collector main by operatin one or};

or blended distlllates, two or more diflerent kinds of tar can be distilled separately at the more days in the manner herein escribed.

If continuous operation with a relatively small amount of tar is desirable, the light or. heavy oil from the condensers can be added in suitable proportion to the tar which is circulated either b spra ing the oil into the collector main or y adding it to the tar or pitch with which the main is flushed. Such operation may be desirable when there is no provision for the accumulation of large stocks of tar.

Where the amount of tar'available for diswhich is so operated or the volume of gases used should be re-.

tillation is limited, it may be desirable to provide a short collector main connected. to the uptake pipes'of several ovens and adapted to receive the hot coke-oven gases therefrom. The .tar to be distilled can be supthe usual condensing system. The short collector main may be disposed advantageously at the rear of the ovens and connected thereto by separate uptake pipes. The same ovens may be connected also to the usual collector main and valves may be arranged in the uptake pipes and connections to permit the discharge of coke-oven gases into either main as desired. The usual collector main may also be replaced by a number of short collector mains each connected to the uptake pipes ofa plurality of ovens and one or more of the short collector mains may be operated as hereinbefore described to distill tar by utilizing the heat of the hot coke-oven gases. In either case the short collector main or mains can be connected to the usual condensing system of the battery or separate condensing systems can be provided. Thus,

all of the volatile products can be condensed directly or'indirectly and fractional conden;

sation may be employed to produce a number of different products from the vapors derived from a single distillation.

The tar'whi h's distilled according to the present invention may be tar produced at thesame coke-oven plant or at another lant. Thetar may be a heavy tar, light tar or eavy or light tar constituents which it is desired to distill for the purpose of separating distlllate oils therefrom. Other tar such as gashouse 'tar, vertical retort tar or water gas tar, etc., can al so be distilled. Where blended or composite pitches are desired or composite coke-oven plant or they pan e admixed in suitableproportions and can be distilled together, giving directly a composite pitch product. Where difierent tars are distilled the resulting pitches can be blendedto give a composite product ahd the distillates can likewise/be blended when desired. For example, horizontal gas-retort tar with high. .free carbon content can be admixed with coke-oven tar andthe mixture-can be distilled to give a composite pitch higher in free carbon than the pitch from the coke-oven tar and to give a composite oil distillate. The tar distilled may contain all or practically all of the condensable oils or it may be a heavy tar containing only part of the oils. lVhere mixed tars are distilled the condensates will be of a composite character. Where different tars are separately distilled the gases and vapors from such separate distillations can be condensed separately or to- -gether.

Tar as commonly produced and collected at coke-oven plants contains more or less water or ammonia liquor admixed therewith. Such tar can be employed directly and dehydrated as well as distilled or it can be partially or completely dehydrated before subjectingit to distillation. The tar can also be preheated in any suitable manner to reduce it to a thinly fluid state which will facilitate the spraying of the tar into the hot coke-oven gases, although the amount of heat contained in the hot coke-oven gases is so great that effective dehydration as well as distillation can readily be effected, and preheating of the tar by separate preheating means Will not usually be necessary.

In carrying out the process the tar may be brought into contact with the hot gases only once or it may be recirculated and again brought into contact with the hot gases to bring about further distillation and the production of harder pitches or even pitches of modified character such as those having increased free carbon content. This further distillation may take place by recirculating the tar or pitch through the same collector main or through another or other systems, as, for example, successively through a series of short collector mains so that distillates and pitch of the same or similar character are produced in the different systems or distillates and pitches of different character in the different systems. By regulation of the rate and type of tar spray and by redistillation when necessary, it is possible to regulate the hardness of the pitches produced and to produce softer or harder pitches as desired. The further distillation of the pitch first produced to recover additional oil therefrom can be carried out in the collector main or in other distillation apparatus. By providing separate collector mains, each connected to a series of ovens, it is possible to produce distillates and pitches of different characteristics simultaneously and by operating separate condensing systems with such separate distillation systems condensed products having different properties can be produced simultaneously.

The present invenion includes not only the distillation of tar for the production of distillate. oils therefrom but also the production of pitches of varying properties and characteristics. By limiting the time of contact of the tar with the hot gases and the temperature to which the tar is raised during distillation, pitches of low carbon content and oils of definite characteristics can be produced as hereinbefore described. lVhen, however, the pitch first produced is recirculated, its temperature will be further raised and the temperature can be increased to such an extent that more or less decomposition will take place with resulting formation of free carbon, thus increasing the free carbon content of the pitch. It is thus possible by recirculation of the pitch and by regulating the spraying operation, so that the pitch is kept in contact with the hot gases for a sufficient time to raise its temperature to the decomposition temperature, to decompose or crack a greater or less amount of the pitch and/or oily constituents and to produce a corresponding amount of free carbon in the product.

In addition to producing pitches of different properties and characteristics, the present invention permits the production of distillates from tar or tar fractions or oils. Consequently it can be employed to distill a dirty oil or an oil contaminated with tar or pitch to produce a cleaner distillate oil therefrom and pitch residue. In systems where separate short collector mains are connected to separate condensing systems, each system may be supplied with a different material, for example; one may distill tar in the manner described and another may distill a mixture of oils for the separation of different oil constituents therefrom.

The gases escapingfrom the collector main operated in the manner hereinbefore described contain considerable quantities of vapors of oils derived from the distillation of the tar together with the usual fixed gases. The gases, being still at a relatively high temperature in order that the oils may be retained in vapor form and thus separated from the pitch, may be subjected to any subsequent desirable treatment for the purpose of effecting the separation of the oil in fractions. Preferably the gases are withdrawn from the centre box of the collector main independently of the pitch circulating therein and are conducted through a cross-over main to the separation apparatus. In order to cool the gases effectively and as rapidly as possible to the temperature desired for the separation of one or more of the volatile constituents, the gases may be sprayed in the cross-over main with ammonia liquor or oil or mixtures thereof and the resulting liquid can be conveyed to a decanter in order to separate the ammonia liquor from the condensed tar or tarry oils.

Instead of cooling the gases and vapors rapidly. they may be cooled progressively to effect a fractional condensation of the vapors. The large increase in condensable vapor content of the gases, due to the distillation of tar thereby, results in the recovery of a greatly increased amount of light tar and oil products while the scrubbing and purifying effect of the tar on the gases gives relatively cleaner oil products than with ordinary by-product condensing systems.

The present invention is of more or less general application to the distillation of tar and oils and the recovery of distillates. The invention involves utilization of the hot cokeoven gases for the distillation of tar or oil by bringing the tar or oil into direct contact therewith. The invention will be further illustrated by the following more detailed description which should be read with the accompanying drawings showing apparatus adapted for the practice of the invention, but it is intended and will be understood that the invention is not limited to specific details of the apparatus as illustrated in the drawings; in which y Fig. 1 is a plan view of a portion of a coke oven battery illustratingthe application of the invention thereto;

Fig. 2 is an end tion, of the structure illustrated in Fig. 1;

Fig. 3 is an enlarged view, partially in section, showing the tar sprays in' the collector main; i y Fig. 4 is a plan view illustrating the application of the invention with a separate short collector main and, separate condensers connected thereto; an

Fig. 5 is a plan view illustrating the application of several short collector'mains an condensingsystems. 1

Referring to the drawings, 5 indicates a battery of coke ovens having individual uptakepipes and goose-necks 6 which connect the ovens with a collector main 7. The latter may be of any usual form and construction and is designed to receive all'of the gases from the individual coke ovens and to deliver them through a center box8 to a cross-over main 9 whichis connected to the condensing ap aratus hereinafter described.

he collector main is provided with a plu rality of spray nozzles 10 distributed throughout its length and connected to pipes 11 which in turn communicate through a pipe.

12. The pipe 12 also supplies tar to pipes 11 connected to spray nozzles 10' in the valve box 12. A pump 14 is provided to force the tar or pitch from a receptacle 15 through pipes 16', 12,11 and 11' to the nozzles 10 and 10'. A pipe 17 is connected to the pipe 12 to ermlt the introduction of tar at the end of the collector main for the purpose of flushing the main. The pitch which accumulates in the bottom of the collector main'is withdrawn through the pipe 15 and may be recirculated through a pump 16 and the pipes 12, 11. 11 and 17 or the pitch can be withdrawn through a pipe 17 and delivered to areceptacle 18.

faces elevation, partially in secexposed surfaces of the main and prevent gases. d agreater -at the temperature at example, a temperature The gases tion of the collector main As hereinbefore described, the operation of the collector main involves the maintenance therein and the circulation therethrough of a suflicient quantity of tar or pitch to prevent the accumulation of hard pitch in the bottom or on the exposed surthereof. The pitch may be withdrawn continuously or intermittently through the pipe 17 to the receptacle 18, or it may be withdrawn through the pipe 15 and returned to the spray nozzles 10 and 10' and the pipe 17 together with tar or pitch from other sources. The tar or pitch in the collector main is subjected by reason of its subdivision in the spray nozzles to intimate contact with the hot coke-oven gases which enter the collector main through the goose-necks. This intimate contact of the gases with the tar or pitch. effects a substan- The sprays of tar or pitch likewise flush the accumulation of hard pitch thereon. The intimate contact between the gases and the tar or pitch in the collector maln serves another important purpose in that it washes from the gases the more readily condensable tar constituents thereof and thus further increases the proportion of volatile constituents in the It further washes from the gases to or less extent much of the entrained solid or liquid material such as free carbon and higher boiling tarry bodies. The gases are thus not only enriched in the more volatile constituents but are freed to some extent from insoluble entrained materials. The volatile oils, which are distilled from the tar or pitch as the result of the absorption of heatfrom the coke-oven gases, remain in the gases which the collector main is operated, for from 100 to 200 C. lower than that of the gases escaping from the coke ovens.

which escape from the centre box 8 to the cross-over main 9 carry therewith a large proportion of the volatile constituents of the tar or oil which enters the collector main and are to a considerable degree freed not only from heavy tar constituents which are not volatile at the temperature of operabut also from insoluble entrained matter. These gases may be subjected in the cross-over mam to contact with ammonia liquor or ammonia liquor and oil delivered thereto through a plurality of spray nozzles. 21 supplied by a pipe 22 from any available source of ammonia liquor in the system. 'From thecross-over main the liquid containing any tar or oil constituents, together with the ammonia liquor, is delivered through a pipe 23 to a decanter 24 thus circulating in which the ammonia liquor can be separated and returned, for example, through the pipe and receptacle 25, pump 26 and pipe 22, to the cross-over main. The tar or oil from the decanter is delivered through a pipe 27 to a receptacle 28 or through the pipe 31 to the tar receptacle 15. A pump 29 and pipe 30 permit delivery of tar or oil from the receptacle 28 to the pipe 22 and the tar or oil to the desired extent can be mixed with ammonia. liquor employed as a cooling agent in the cross-overmain. A draw-ofi line 30' permits withdrawal of the product from the receptacle 28. Tar from any other source can be delivered to the receptacle 15 through a pipe 20'.

The balance of the gases still containing oil constituents are delivered to condensers 32 wherein the available oil products are separated and from which they can be withdrawn to a decanter 33 for separation of ammonia liquor from the oil, The gases which escape from the condensers 32 are withdrawn through the exhauster 34 which ensures movement of the gases through the system.

As hereinbefore indicated, the primary object of the present invention is the distilla tion of tar and the recovery of volatile constituents therefrom at the coke-oven plant and the utilization of heat in the gases escaping from the coke ovens. An advantage of the invention as described is that in conducting the distillation the usual collector main is utilized with slight modificaton and the difficulty heretofore experienced inkeeping the collector main free from accumulations of hard pitch ,is avoided. In the illustrated embodiment of the invention a single collector main is employed, but it istobe understood that a short collector main or plurality of such collector mains may be connected each to a plurality of coke ovens for the purpose of carrying out the invention and that one or more condensing systems may be provided when necessar or desirable for the accomplishment of the intended purpose.

In Fig. 4 of the drawings the arrangement of the apparatus permitting the use of separate collector mains is illustrated. The cokeoven battery 35 is provided with the usual uptake pipes and goose-necks 36 which communicate with-the collector main 37 having a center box 38 from which the gases and the condensate are delivered to a cross-over main 39 leadin to the usual condenser system including t e condensers 40. The gases. are drawn through the system by an exhauster 41. The se arated tar and ammonia li uor may be wit drawn through decanters shown) as in the usual practice. The structure so far as described is the ordinary arrangement and in the operation of this apparatus ammonia liquor in suitable quantity may be delivered to the collector main forf the purpose of cooling the gases therein.

not

To permit the practice of the invention as herein described a number of the uptake pipes and goose-necks 42 are connected to a separate short collector main 43 which may be disposed alongside of, above, or in any other suitable relation to the primary collector main but is preferably arranged at the rear of the ovens. The short or auxiliary collector main is designed for the distillation of tar in the manner hereinbefore described and is provided, therefore, with a plurality of spray nozzles 10 as in Fig. 3 so arranged as to permit the spraying of silfiiciently large quan tities of tar into the main for the purpose of preventing the accumulation of itch therein. The spray nozzles are supplied with tar or tar and pitch through pipes 44 and 45 and the main can be flushed with tar introduced through a pipe 46. Additional tar or pitch can be supplied through a pipe 47. In the short or auxiliary collector main the tar is intimately mingled with the hot gases from the coke ovens with the result that the tar'is distilled and the more volatile constituents thereof are carried away with the ases. The pitch and tar are withdrawn continuously or intermittently throu h a pipe 48 and can be returned by means 0' a pump 49 to the spray nozzles for further treatment in the main ortransferred throu h a pipe 50 to a receptacle for the pitch pr6 uced.

p The gases from the short or auxiliary collector main are withdrawn through a cross over main 51 and delivered to condensers 52. These can be arranged in series and may be fractional condensers to permit the recovery of several different products from the gases leaving the short collector main. The condensate from the condensers 52 can be withdrawn and delivered to a suitable receptacle. The remaining-gases may then pass through a pipe 53 to the exhauster 41 which maintains the proper pressure in the s stem.

' In F ig, 5 of the drawings have illustrated another arrangement in which the usual collector main is replacedby a number of short collector mains,.each connected to the uptakes from a plurality of ovens. Each of the collector mains may be providedfivith tar sprays and circulating means to permit the flushing of the mains with tar or tar and pitch' in the manner hereinbefore described. This arrangementvis advantageous in. that itpermits the operationof one or more ofthe" short 'collector mains for tar distillation while the other mains are. operated in the usual way with sprays of ammonia liquor to cool the gases therein. Thus, the equipmelitis adapted forthe distillation of more or less tar depending u on the amount which may be available for distillation in the plant at different times. I

; .Referring to the drawings, the coke oven battery 55 is provided with the usual uptake pipes and goose-necks 56.' A number of short collector mains 57 are provided and each is connected to a plurality of the goosei'iecks 56. Cross-over mains 59 are provided to connect each of the collector mains with the usual condenser system including the condensers 60. The gases are drawn through the system by an exhauster (31. The sepa rated tar and ammonia liquor may be withdrawn through decanters (not shown) as in the usualpractice. Thestructure and operation, so faras described. are, except for the substitution of the short collector mains,

' similar to that usually employed.

' mains with the tar or tar and pitch.

To permit the practice of the invention as herein described, each of the short collector mains is provided with a plurality of spray nozzles as in Fig. 3 and with pipes 53 connected to the spray nozzles and to the collector mains so as to permit the introduction of tar or tar and pitch through the spray nozzles and, if desired, to the ends of the collector mains to permit flushing of the collector Pipes Mare arranged to withdraw the tar or pitch from the collector mains and pumps 55 may return all or a portion of the tar or pitch to the spray nozzles or otherwise to the mains. A portion of the tar or pitch can be withdrawn through pipes 56 and delivered to a suitable receptacle. Fresh tar or pitch can be supplied through pipes 5". Each of the short collector mains is thus adapted for the distillation of tar and for the introduction of a sufficient quantity of tar or tar and pitch to prevent the accumulation of pitch therein. In the short collector mains in which tar or tar and pitch is intimately mingled with the 'hot' gases from the coke ovens the tar or tar and pitch is distilled and the more volatile constituents thereof are carried away with the gases.

When, therefore, the short collector mains are employed for distillation, the gases escaping therefrom may, if desired, be conducted to the separate condensing systems including condensers 62. These can be arranged in series and may be fractional condensers to permit the recovery of several different products from the gases leaving the short collector main or mains. The condensate from the condensers 62 can be witli-' the proper pressures in the system.

The arrangement as described permits the operation of the coke oven in the usual manner and the utilization of a portion of the heat in the hot cokeoven gases for the purpose of distilling tar derived from the gases issuing from the other ovens of the battery or tar from other sources. As in the tar distillation in the collector main as previously described, it is essential to flush the short or auxiliary collector main with a quantity of at isolated coke-oven plants Where a single battery of coke ovens is operated and Where the quantity of tar obtainable from other sources is relatively limited. It permits the production of pitch having the desired characteristics and the recovery of valuable oils from the tar in a simple, effective and economical manner.

fThe advantages of the invention have been set forth in some detail and the preferred embodiments have been described. It is to be understood, however, that various changes may be made in the operation as described without departing from the invention or sacrificing the advantages enumerated or any other advantageous results which may be accomplished by the application of the principles set forth.

In the accompanying claims I use the term tar to include not only the raw tar, but also the partly distilled tar or tarry oils which are introduced into the main and atomized or sprayed intothe gases and distilled thereby.

Iclaim:

1. The improvement in the operation of coal distillation plants with distillation of tar and production of pitch and oils therefrom and from the coal distillation gases,

same amount of vapor as when they left the ovens or retorts and are still at a temperature sufficiently high to effect rapid distillation of tar and not greatly below that at which the gases leave the ovens or retorts, continuously introducing into the said main a. quantity of tar many times in excess of that contained in such gases and causing the tar tobe atomized or sprayed in a finely divided state into intimate contact with such gases to effect rapid distillation of the tar and to scrub the gases so that the gases are considerably enriched in oil vapors and cleaned by the scrubbing treatment, continuously remov ng from the main the gases and vapors resulting from the distillation and cooling the same to condense oils therefrom, and withdrawing from the main the residue from the distillation.

2. The method of distilling tars and of producing pitches and distillate oils therefrom and of simultaneously producing pitches and oils from coal distillation gases, which comprises conveying the gases from a plurality of coal distillation ovens or retorts, sufficient in number to give an approximately unii 1..

form combined gas flow, and While at a suiticiently high temperature to effect rapid distillation of the tar, to a collector main, maintaining in the main a continually moving and changing body of tar and pitch, introducing the gases into the main above the body of tar and pitch therein continuously introducing into the main the tar to be distilled in an amount several times that normally contained in the gases passing through the main and causing the tar to be atomized or sprayed in a finely divided state into the gases and against the Walls of the main above the body of tar therein to effect rapid distillation of the tar and simultaneous scrubbing and rapid cooling of the gases and washing of the exposed sides of the main, so as to prevent the carbonization of pitch thereon, whereby pitch is scrubbed from the gases and combined with the body of tar and pitch at the same time that the tar is rapidly distilled and the resulting distillate oil vapors are combined with the gases passing through the main, passing the resulting gases and vapors to a condensing system to condense oils therefrom, and drawing on the resulting pitch from the main.

In testimony whereof I aiiix my signature.

STUART PARMELEE MILLER. 

